[1]} suggests that the QPO frequencies range from \(\sim \) mHz to kHz (\(\leqslant \) 1.2 kHz). Based on the peak frequency (\(\nu \) ), QPOs are categorized into low-frequency QPOs (LF–QPOs) and high-frequency QPOs (HF–QPOs). In the case of BHXRBs, the LF–QPOs are characterized by 0.1 \(\le \)  \(\nu \)  \(\le \)  30 Hz. Using the definition of the Quality factorQ–factor is defined as the ratio between the QPO centroid frequency and the full width at half maximum (FWHM) of the QPO peak.(also referred to as Q–factor), representing the broadness of a QPO peak [2]}, the LF–QPOs are further sub-categorized into three types: Type–A, Type–B and Type–C [3]}, [4]}. Type–A LF–QPOs are characterized by a weak (few percents of rms amplitude) and broad peak (Q–factor \(\le \)  3) around 7–9 Hz, usually observed on top of weak red noise [3]}, [6]}. Type–B LF–QPOs represent a relatively strong ( \(\sim \) 4\(-\) 7% rms amplitude) and narrow peak (Q–factor \(\sim \) 5–7) between 5\(-\) 7 Hz, usually associated with a weak red noise (few percent rms) [7]}. The type–C LF–QPOs are characterized by a strong (up to \(\sim \) 21% rms amplitude) and narrow peak (Q–factor \(\sim \) 5–12) with the variable centroid frequency between 0.1–15 Hz superposed on a strong flat-top noise [8]}, [9]}.
